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J. R. CARSON. TRANSLATING CIRCUITS. APPLICATION man ocr. 10, 1910.

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A TTORNEY Patented Aug. 5, 1919.

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JOHN R. CARSON, OF NEW YORK, N. Y., ASSIGNOR TO AMERICAN TELEPHONE AN'D TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

TRAN SLATING-CIRCUITS.

Specification of'Letters Patent.

Patented Aug. 5, 19119.

Application filed October 10, 1918. Serial No. $57,655.

To all whom it may concern:

Be it known that I, JOHN R; (Larson, residing at New York, in the county of New York and State of New York, have invented certain Improvements in Translating-Circuits, of which the following is a specification. r

This invention relates to signaling circuits, and more particularly to signaling circuits of the type in which carrier currents are employed for the transmission of signals.

The invention has for one of its objects the provision of a translating arrangement in which there is no input or controlling circuit a distinguished from the output or controlled circuit, the functions of the two circuits being combined ina single operating circuit associated with the translating device. Another object of the invention is to produce a translating arrangement of this character which may {be used either for modulating high frequency oscillations in accordance with signal variations, or for detecting the signals imposed upon high frequency carrier oscillations, by the inter action of the modulated oscillations with a local source of oscillations in accordance With the heterodyne or homodyne principle of receiving. Still another object of the invention has reference to the provision of a translating arrangement of the character above described in which the unmodulated oscillations are ineffective on the outgoing circuit when the modulating source is in-' active, so that, when the arrangement is used for modulating high frequency oscillations in accordance with signal waves, the resultant modulated oscillations impressed upon the outgoing circuit will have an amp itude directly proportional to that of the modulating wave. Other and further objects of the invention .will be clearer from thedetailed description hereinafter appearlng.

The objects of the invention are secured a herein disclosed by employing as the translating device a three-element vacuum tube having a heated filament, an anode or plate and a controlling electrode or grid,

the controlling electrode and anode being directly connected together, and having .an operating circuit extending therefrom to the filament, upon which both the unmodulated a The invention may now be morefully understood by reference to the following description when read in connection with.

the accompanying drawing, in which Figures 1, 2 and 3 constitute circuit diagrams of three difl'erent modifications of the invention.

Referring to. Fig. 1, a vacuum, tube 1,

having a heated filament 2, an anode or plate 3 and a controlling electrode or grid 4, isshown, the controlling electrode 4 and the plate 3 being directly strapped together. A single operating circuit 5 extends from the connection between the grid and plate to. the filament 2 and includes a source of direct current. 6 for providing the space current'of the tube. A source of high frequency oscillations 7 is associated with the operating circuit 5 through a transformer 8,

and a circuit 9. leading to 'a modulating source is'coupled to the operating circuit 5, through a transformer 10. The circuit 9 may lead eitherto a source of low frequency signaling waves, or to a source of hi h fre quency oscillations modulated in accordance with asignal at adistant station, depending upon Whether the arrangement is to be use for modulating. high frequency oscillations at a sending station in accordance with signals, or as a modulating detector. for receiving modulated or high frequency oscillations transmitted from a distant station. An

outgoing circuit 11 is also coupled to the operating eircuit 5 through a transformer 12, and serves to lead off modulated osclllations if desired. A source of direct current 13 may be included between the grid and the plate in order to impress upon the grid a potential of such character as to secure the most efficient operation of the tube,

preferably this source should be of such a character as to render the grid somewhat negative with respect to the plate.

In operation, the evacuated space between the filament 2 and the plate 3 serves as athe transformer 12 to the outgoing circuit 11. If the arrangement is to be used for modulating high frequency oscillations in accordance with low frequency signal waves, the signal waves will be impressed upon the circuit 9 and the modulated oscillations will be transmitted to the circuit 11. If the arrangement is to be used as a modulatlng detector for detecting modulated high fre-.

quency oscillations transmitted from a distant station, the modulated high frequency oscillations will be impressed upon the circuit 9 and by their interaction with the oscillations from the constant source 7 will result in the transmission to the circuit 11 of low frequency waves corresponding to the modulating signal wave. The source of oscillations 7 should be of the same frequency as the source of carrier oscillations modulated at the distant station if the arrangement is to detect upon the homodyne principle, while if it is to be employed in accordance with the heterodyne principle the frequency of the source 7 should differ from that of the received oscillations by an amount suflicient to cause an audible beat frequency in the circuit 11.

A slightly modified arrangement is shown in Fig. 2 which difiers from that of Fig. 1 in that the operating circuit 5 is provided with two branches 14 and 15, the former including the direct current source 6 and the secondary of the transformer 10, by which the circuit 9 is associated with the operating circuit, while the branch 15 includes the primary of thetransformer 12 through which the outgoing circuit 11 is associatedwith the operating circuit 5. The source of high frequency oscillations 7 is coupled through a transformer 8 to a common conductor of the circuit5. Since the arrangement functions in substantially the same manner as that already described in connection with Fig.7 1, no further description is necessary.

here it is desired to render the source of unmodulated high frequency oscillations inefiective upon the outgoing circuit when the modulating source is inactive, a duplex circuit, such as is illustrated in Fig. 3, may be employed. In this case the modulating tubes 16 and 17, having filaments 18 and 19, plates 20 and 21, and grids 22 and 23,'are employed. Each of thetubes is provided with an operating circuit arrangement sin1ilar to that of Fig. 2. The operating circuits 24 and 25 of the two tubes have a common conductor 26 in which is included the direct current source 6 and the secondary winding of the transformer 8 through which the source of high frequency oscillations 7 is associated with the modulating tubes. The circuit 9 leading to the modulating source is associated with the operating circuits 2 1 and 25 through a transformer arrangement 27 having windings in each of the operating circuits. In a similar manner the outgoing circuit 11 is associated with the operating circuits 24 and 25 by a transformer arrangement 28.

It will be seen that the source of oscillations 7 is associated with the tubes 16 and 17 by means of a circuit which is balanced with respect to the outgoing circuit 11, provided the conductivity of the two tubes is the same, so that normally no efiect is produced upon the outgoing circuit 11. When, however, modulating waves are impressed upon the circuit 9, the potentials upon the grids 22 and 23 are varied in such a manner as to disturb the balance of the circuits in proportion to the amplitude of the modulating wave, so that modulated high frequency oscillations are transmitted through the transformer 28 to the circuit 11, the amplitude of said oscillations being directly proportional to that of the modulating wave.

As inthe case of the modification shown in FigsQl and 2, this arrangement may also be used either for modulating high frequency oscillations in accordance with signal waves, or for detecting, in' accordance with the homodyne or heterodyne principle of receiving, modulated high frequency oscillations transmitted. from the" distant illustrated without departing from the spirit I of the invention as defined in the following claims.

What is claimed is 1. In a signaling system, a modulating device comprising an evacuated tube including a heated filament, an anode and aicontrolling electrode, said anode and controlling electrode being directly connected, a single operating circuit for said tube extending, from said filament to said directly connected anode and controlling electrode, and a source of unmodulated oscillations and a source of Variable oscillations connected with said operating'circuit.

2. In a signaling system, a modulating device comprising an evacuated tube including a heated filament, an anode and a control-.

ling electrode, said anode and controlling electrode being directly connected, a single operating circuit for said tube extending from said filament to'said directly connected anode and controlling electrode, and a source of unmodulated oscillations, a source of variable oscillations and an outgoing circuit connected with said operating circuit.

'3. In a signaling system, a modulating device comprising an evacuated tube including a heated filament, an anode and a controlling electrode, said anode and controlling electrode being directly connected, a single operating circuit for said tube extending from said filament to said directly connected anode and controlling electrode, and a source of unmodulated oscillations and a source of modulating signal waves connected with said operating circuit.

4. In a signaling system, a modulating device comprising an evacuated tube including a heated filament, an anode and a control ling electrode, said anode and controlling electrode being directly connected, a single operating circuit for said tube extending from said filament to said directly connected anode and controlling electrode,and a source of unmodulated oscillations, a source of modulated signal waves and an outgoing circuit connected with said operating circuit.

5. In a signaling system, a modulating arrangement comprising a 'pair of evacuated tubes each including a heated filament, an anode and a controlling electrode, the anodes and controlling electrodes of each tube being directly connected, a single operating circuit for each tube extending from the filament to the directly connected anode and controlling electrode of the tube, and a source of unmodulated oscillations and a source of variable oscillations connected with said operating. circuits. I

6. In a signaling system, a modulating arrangement comprising a pair of evacuated tubes each including aheated filament, an

anode and a controlling electrode, the anodes andcontrolling electrodes of each tube bea ing' directly connected, a single operating circuitfor each tube extending from the filament to the directly connected anode and controlling electrode of the tube, and a source of unmodulated oscillations, a source ofvari- 7 able oscillations, and an outgoing circuit connected with said operating circuits.

7. In a signaling system, a modulating arrangement comprising a pair of evacuated tubes each including a heated filament, an an- 7 ode and a controlling electrode, the anodes and controlling electrodes of each tube being directly connected, a single operating circuit for each tube extending from the filament to the directly connected anode and control- 8 ling electrode of the tube, and a source of unmodulated oscillations and a source of modulating signal Waves connected. with said operating circuit.

8. In a signaling system, a modulating 8 arrangement comprising a pair .of evacuated tubes each including a' heated fi la' ment, an anode and a controlling electrode, the anodes and controlling electrodes of each tube being directly connected, a single 9 operating circuit for each tube extending from the filament to the directly connected anode and controlling electrode of the tube, and a source of unmodulated oscillations,

a source of modulating signal waves and 9 an outgoing circuit connected with said operating circuits.

9. In a signaling system, a modulating arrangement comprising a pair of eva'ouated tubes each including a heated filall ment, an anode and a controlling electrode, the anodes and controlling electrodes of each tube being directly connected, a single operating circuit for each tube extending from the filament to the directly connected anode and controlling electrode of the tube, and a'source' of unmodulated oscillations and a source of variable oscillations connected with said operating circuits, the connection of said sources and said outgoing circuit to said operating circuits being such that said first mentioned source'is without effect upon-said outgoing circuit when said second mentioned source is inactive.

10. In a signaling system, a modulating arrangement comprising a pair of evacuated tubes each including a heated filament, an anode and a controlling electrode the anodes and controlling electrodes 0 each tube being directly connected, a single operating circuit for each tube extending from the filament to the directly connected anode and controlling electrode of thetube, and a source of unmodulated oscillations, a source of variable oscillations, and an outgoing circuit connected with said operatingcircuits, the connection of said sources and said outgoing circuit to said operating circuits being such that said first mentioned source is Without effect upon said outgoing circuit When said second mentioned source the anodes and controlling electrodes of each tube being directly connected, a single operating circuit for each tube extending from the filament to the directly connected anode and controlling electrode of-the tube, and a source of umnodulated oscillations and a source of modulating signal Waves connected With said operating circuit, the connection of said sources and said outgoing circuit to said operating circuits being such that said first mentioned source is Without 'efl'ect upon said outgoing circuit when said second mentioned source is in active.

12. In a signaling system, a modulating arrangement comprising a pair of evacuated tubes each including a heated filament, an anode and a controlling electrode, the anodes and controlling electrodes of each tube being directly connected, a single operating circuit for each tube extending from the filament to the directly connected anode and controlling electrode of the tube, and a source of unmodulated oscillations, a source of modulating signal Waves and an outgoing circuit connected With said operating circuits, the connection of said sources and said outgoing circuit to said operating circuits being such that said first mentioned source is Without efi'ect upon said outgoing circuit When said second mentioned source is inactive.

In testimonyv whereof, I have signed my name to this specification this 7th day of October, 1918.

- JOHN R. CARSON. 

